I have had my Fitbit Blaze for about one year and a half years. I purchased it on Amazon,jp.co. in Japan (July 22, 1916). Fitbit couldn't exchange my watch because the seller was not a participating partner. Since the Fitbit Blaze was older than one year, the seller apologized saying it was past the warranty. My watch would last for two or three days after charging with regular use.
A typical use for me is a thirty-minute workout Monday to Friday. I also like to do a six-kilometer meter walk ( 2 hours) two-three days a week. I also monitor my heart 24/7 and my sleep. I like the watch, and it has become part of my lifestyle, and I don't want an Apple watch.
April 18th The Fitbit blaze is still holding its charge. I don't know if this makes a difference and I haven't put it
Solution: I was sure it was the firmware that caused this problem. But I accidentally shut down my watch placed it in the cradle connected to an a/c nugget and allowed it to charge for 2 hours. And behold it has been holding its charge with no problem for four days. It can hold for the fifth day, but you run the risk of no charge in the morning or early afternoon.
Conclusion: Shut down whenever you want to charge your Fitbit Blaze. I don't know if this will be detrimental to the longevity of the watch ( 2 years), but I have had no issues, and it beats buying a new one.
UPDATE:
It is April 18th, 2018 and the Fitbit Blaze is still holding its charge for four days even up to five days. The only other thing that I have done was change the face clock *black background, red time, white day, month, date, and heart rate." I have not tried the other clock faces to see if that was the problem.
